I usually go a bit overkill on article spinning, but thats just me. I also write my own content just so I can play around with various LSI's and related keywords that I want to target for future campaigns with the same article.
If I want something that'll last me a LONG time, I hand-spin (human readable/high uniqueness) on the word<->phrase->paragraph level. I also rewrite each paragraph but keep the keyword densities for that paragraph the same, then spin those two together. So for each block paragraph, there are actually two separate paragraphs. I sometimes even go further than that, depending on how often I want to use that article. I do this to keep the flow of the article at a relatively decent quality while being able to spit out a very large amount of articles without worrying about search engines and duplicates.
I guess my reasoning behind this is I might as well future proof things in case Google comes out with some new grammar algo. I can't quite find a program to judge the uniqueness of it accurately... Article Marketing Robot says the article I am currently spinning is at 700% uniqueness. ._.